Background: Although many dysphagia screening tools exist, none has high sensitivity and reliability or can be administered quickly with minimal training. Objective: To design and validate a swallowing screening tool to be used by health care professionals who are not speech language pathologists to identify dysphagia and aspiration risk in acute stroke patients. Methods: In a prospective study of 300 patients admitted to the stroke service at an urban tertiary care hospital, interrater and test-retest reliabilities of a new tool (the Acute Stroke Dysphagia Screen) were established. The tool was administered by nursing staff when patients were admitted to the stroke unit. A speech language pathologist blinded to the results with the new tool administered the Mann Assessment of Swallowing Ability, a clinical bedside evaluation, with dysphagia operationally defined by a score less than 178. Results: The mean time from admission to screening with the new tool was 8 hours. The mean time between administration of the new tool and the clinical bedside evaluation was 32 hours. For the new tool, interrater reliability was 93.6% and test-retest reliability was 92.5%. The new tool had a sensitivity of 91% and a specificity of 74% for detecting dysphagia and a sensitivity of 95% and a specificity of 68% for detecting aspiration risk. Conclusions: The Acute Stroke Dysphagia Screen is an easily administered and reliable tool that has sufficient sensitivity to detect both dysphagia and aspiration risk in acute stroke patients.